This invention relates generally to computed tomography (CT) imaging, and more particularly, to methods and apparatus for artifact reduction in a CT systems that are particularly useful for such systems having a wide bore geometry.
In many clinical applications of computed tomography imaging, a larger gantry opening is useful. For example, in oncology applications, a large bore size allows a patient to be positioned in fashion similar to the position of a patient in a radiation treatment machine, which typically has a large opening. When computed tomography scanners are used to aid in performing interventional procedures, an operator's access to a patient is limited by the bore size. In at least one known computed tomography system, both the x-ray tube and the detector are positioned away from the isocenter to increase the operator's access. However, to save development cost as well as flexibility of an adjustable geometry, a detector designed for the original geometry is used, rendering the arc of the detector of the imaging device no longer concentric to a focal spot of the x-rays. As a result, image artifacts are introduced in reconstructed images because the x-ray path is no longer the original path assumed by the reconstruction process.